Explanation:
One of the largest spheres in
our Galaxy
is giving valuable clues about the chemical composition
of stars by its very shape.
Planetary nebulaAbell 39, now six light-years across, was once
a sun-like star's outer atmosphere expelled thousands of years ago.
The nearly perfect
spherical nature of
Abell 39 allows astronomers to accurately
estimate how much relative material is actually
absorbing and emitting light.
Observations indicate that
Abell 39
contains only about half of the
oxygen found in the
Sun,
an intriguing but not surprising confirmation of the
chemical differences between stars.
The reason why the central star is slightly off centre by 0.1
light-years is currently unknown.
Abell 39 lies about 7000 light years away, although several
galaxies
millions of light years away can be seen through
and around the nebula.